The BMWM10 was a straight-4SOHCpiston engine produced from 1962 to 1988 with displacements ranging from 1499 cc to 1990 cc. The engine was very successful, with over 3.5 million produced across many BMW models.[1] It was also used as the basis for the turbocharged BMW M12 motorsport engine which produced over 700 kW.

The engine was designed by noted engineer and race driver Baron Alex von Falkenhausen.[1] In the late 1950s, he was asked to design a small-displacement (1.3 L) engine, but felt that this would be insufficient for the company's future needs. Therefore, he convinced BMW that the capacity should be 1.5 L instead and he designed a block that could be expanded to 2.0 L in the future.

The engine was initially known as the "M115" (the last two digits representing the 1.5 litre capacity). Over the years, variants of the engine were given various codes (most of them starting with "M1..." and the remaining digits relating to the capacity). In 1975, the engine became known as then "M10", then in 1980 it was given the standardised BMW engine code of M10B18 (where "M10" represents the series and the "18" represents the 1.8 litre capacity).

The M115 and all related engines have become retrospectively known as the "M10" family.